I can only go off what you have written.
A 4 year old losing it over a teacher not getting him paper (when he didn't ask for it) signals a bigger issue to me.
I never said you said that. Again, I'm basing it off the info provided, not his whole life.
And, as you said, daycare haven't mentioned it before- that doesn't mean it's not happening.
I agree that they shouldn't have mentioned it so casually, but maybe they felt it was the best way? Perhaps they have mentioned ASD to other parents and they have freaked?